21234555 has 24 divisors (see below), whose sum is σ = 38171952. Its totient is φ = 11324448.

The previous prime is 21234541. The next prime is 21234593. The reversal of 21234555 is 55543212.

It is a happy number.

It is not a de Polignac number, because 21234555 - 2⁵ = 21234523 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7524 + ... + 9953.

It is an arithmetic number, because the mean of its divisors is an integer number (1590498).

Almost surely, 2^21234555 is an apocalyptic number.

21234555 is a deficient number, since it is larger than the sum of its proper divisors (16937397).

21234555 is an equidigital number, since it uses as much as digits as its factorization.

21234555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17497 (or 17485 counting only the distinct ones).

The product of its digits is 6000, while the sum is 27.

The square root of 21234555 is about 4608.0966786733. The cubic root of 21234555 is about 276.9157906737.

Adding to 21234555 its reverse (55543212), we get a palindrome (76777767).

The spelling of 21234555 in words is "twenty-one million, two hundred thirty-four thousand, five hundred fifty-five".